Coupled-inductor-based power-device circuit topology

ABSTRACT

According to an aspect of the present disclosure, an uninterruptible power supply (UPS) system is provided. The UPS system includes a first input configured to be coupled to an input power source, a second input configured to be coupled to an energy storage device, an output configured to provide output power, a power conversion circuit (PCC) configured to convert power received from at least one of the input power source or the energy storage device, an output circuit coupled to the PCC and the output, and a controller. The PCC includes a first inductor and a second inductor magnetically coupled to the first inductor. The controller is configured to control the PCC to provide, via the first inductor, DC power derived from the input power source to the output circuit, and provide, via the first and second inductors, DC power derived from the energy storage device to the output circuit.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under 35 U.S.C. § 119 to Indian PatentApplication No. 201911032134, titled “COUPLED-INDUCTOR-BASEDPOWER-DEVICE CIRCUIT TOPOLOGY,” filed on Aug. 8, 2019, which is herebyincorporated by reference in its entirety.

BACKGROUND OF THE INVENTION 1. Field of the Invention

At least one example in accordance with the present invention relatesgenerally to power devices.

2. Discussion of Related Art

The use of power devices, such as UPSs, to provide regulated,uninterrupted power for sensitive and/or critical loads, such ascomputer systems and other data processing systems, is known. Knownuninterruptible power supplies include on-line UPSs, offline UPSs, lineinteractive UPSs, as well as others. Online UPSs provide conditioned ACpower as well as back-up AC power upon interruption of a primary sourceof AC power. Offline UPSs typically do not provide conditioning of inputAC power, but do provide back-up AC power upon interruption of theprimary AC power source. Line interactive UPS s are similar to off-lineUPS s in that they switch to battery power when a blackout occurs butalso typically include a multi-tap transformer for regulating the outputvoltage provided by the UPS. Certain UPSs can include multiple powerconversion stages.

SUMMARY

According to at least one aspect of the present disclosure anuninterruptible power supply (UPS) system including a first inputconfigured to be coupled to an input power source, a second inputconfigured to be coupled to an energy storage device, an outputconfigured to provide output power, a power conversion circuitconfigured to convert power received from at least one of the inputpower source or the energy storage device, the power conversion circuitincluding a primary branch portion having a first inductor, and a backupbranch portion having a second inductor, the second inductor beingmagnetically coupled to the first inductor, an output circuit coupled tothe power conversion circuit and to the output, and a controller coupledto the power conversion circuit and to the output circuit, andconfigured to control the power conversion circuit to provide, in anormal mode of operation via the first inductor, DC power derived fromthe input power source to the output circuit, and control the powerconversion circuit to provide, in a backup mode of operation via thefirst inductor and the second inductor, DC power derived from the energystorage device to the output circuit.

In an embodiment, the output circuit includes a first capacitorconfigured to be coupled to the power conversion circuit and a secondcapacitor configured to be coupled to the power conversion circuit. Inone embodiment, the primary branch portion includes a third inductor,and the backup branch portion includes a fourth inductor, and whereinthe third inductor is magnetically coupled to the fourth inductor. In atleast one embodiment, the second inductor is coupled to a firstswitching device, and wherein the fourth inductor is coupled to a secondswitching device. In some embodiments, the controller is furtherconfigured to control the first switching device to charge a firstcapacitor, and is configured to control the second switching device tocharge a second capacitor.

In at least one embodiment, the controller is further configured tocontrol the first switching device to charge the first capacitor at afirst rate and is configured to control the second switching device tocharge the second capacitor at a second rate different than the firstrate. In some embodiments, the controller is further configured tocontrol the first switching device and the second switching device tocharge the first capacitor simultaneously with the second capacitor.

In some embodiments, controlling the first switching device to chargethe first capacitor includes controlling the first switching device toenable the energy storage device to provide current to the secondinductor, wherein providing current to the second inductor includesinducing a voltage across the first inductor, and controlling the firstswitching device to disable the energy storage device from providingcurrent to the second inductor, wherein the first inductor is configuredto discharge to the first capacitor responsive to the switching devicedisabling the energy storage device.

In at least one embodiment, controlling the second switching device tocharge the second capacitor includes controlling the second switchingdevice to enable the energy storage device to provide current to thefourth inductor, wherein providing current to the fourth inductorincludes inducing a voltage across the third inductor, and controllingthe second switching device to disable the energy storage device fromproviding current to the fourth inductor, wherein the third inductor isconfigured to discharge to the second capacitor responsive to theswitching device disabling the energy storage device.

In some embodiments, the output power includes an output waveform havinga positive portion and a negative portion, and the positive portion ofthe output waveform is derived from power provided by the firstcapacitor, and the negative portion of the output waveform is derivedfrom power provided by the second capacitor. In one embodiment, theprimary branch portion is galvanically isolated from the backup branchportion. In some embodiments, the backup branch portion further includesa switching device having a first connection coupled to the energystorage device and a second connection switchably coupled to the secondinductor, and a diode having an anode connection coupled to the firstconnection of the switching device and a cathode connection coupled tothe second connection of the switching device.

In at least one embodiment, the system further comprises a switchingdevice including a first connection coupled to the output, and a secondconnection configured to be coupled to one of the output circuit or thefirst input, wherein the controller is configured to control theswitching device to connect the second connection to the first input ina bypass mode of operation, and is configured to control the switchingdevice to connect the second connection to the output circuit in thenormal mode of operation and the backup mode of operation. In someembodiments, the system further comprises a first diode having a cathodeconnection coupled to the first inductor, and an anode connectioncoupled to a reference node, and a second diode having a cathodeconnection coupled to the reference node, and an anode connectioncoupled to the third inductor.

According to at least one aspect of the disclosure, a system is providedincluding a first input configured to be coupled to an alternatingcurrent (AC) power source, a second input configured to be coupled to anenergy storage device, an output configured to provide output powerderived from at least one of the first input or the second input, anoutput circuit coupled to the output, the output circuit including apositive direct current (DC) bus and a negative DC bus, and means forindependently providing power derived from at least one of the firstinput or the second input to the positive DC bus and the negative DCbus.

In one embodiment, the output circuit includes a first capacitor and asecond capacitor. In at least one embodiment, the system furtherincludes means for charging the first capacitor at a first rate andmeans for charging the second capacitor at a second rate different thanthe first rate. In some embodiments, the system further includes meansfor charging the first capacitor and the second capacitorsimultaneously. In an embodiment, the output power is AC power having apositive portion and a negative portion, and wherein the positiveportion of the output power is derived from power provided by the firstcapacitor, and wherein the negative portion of the output power isderived from power provided by the second capacitor. In someembodiments, the second input is galvanically isolated from the outputcircuit. In at least one embodiment, the system further includes meansfor providing output power derived from the first input to the outputand bypassing the output circuit.

According to at least one aspect of the disclosure, a non-transitorycomputer-readable medium storing thereon sequences ofcomputer-executable instructions for controlling a power device isprovided comprising a first input to receive first input power, a secondinput to receive second input power, an output to provide output power,an output circuit to provide the output power to the output, and a powerconversion circuit including a primary branch portion having a firstinductor, and a backup branch portion having a second inductor, thesecond inductor being magnetically coupled to the first inductor, thesequences of computer-executable instructions including instructionsthat instruct at least one processor to control one or more switchingdevices in the power device to receive, by the first inductor in anormal mode of operation, the first input power, provide, by the firstinductor in the normal mode of operation, first power derived from thefirst input power to the output circuit, receive, by the second inductorin a backup mode of operation, the second input power, store, by thesecond inductor in the backup mode of operation, first stored energyderived from the second input power, store, by the first inductor in thebackup mode of operation, second stored energy derived from the firststored energy, and provide, by the first inductor in the backup mode ofoperation, second power derived from the second stored energy to theoutput circuit.

In some embodiments, the output circuit includes a first capacitor and asecond capacitor, wherein the primary branch portion further includes athird inductor, and wherein the backup branch portion includes a fourthinductor magnetically coupled to the third inductor, the sequences ofcomputer-executable instructions further including instructions thatinstruct the at least one processor to control the one or more switchingdevices to provide, by the first inductor and the third inductor, afirst charging current to the first capacitor and a second chargingcurrent to the second capacitor.

In at least one embodiment, the sequences of computer-executableinstructions further including instructions that instruct the at leastone processor to control the one or more switching devices to providethe first charging current to the first capacitor at a first rate andprovide the second charging current to the second capacitor at a secondrate, wherein the first rate is different than the second rate andwherein the first charging current is provided simultaneously with thesecond charging current.

In some embodiments, the power device further includes a switchingdevice having a first connection coupled to the output, and a secondconnection configured to be coupled to one of the output circuit or thefirst input, and wherein the sequences of computer-executableinstructions further include instructions that instruct the at least oneprocessor to control the switching device to connect the secondconnection to the first input in a bypass mode of operation, and tocontrol the switching device to connect the second connection to theoutput circuit in the normal mode of operation and the backup mode ofoperation

BRIEF DESCRIPTION OF THE DRAWINGS

Various aspects of at least one embodiment are discussed below withreference to the accompanying figures, which are not intended to bedrawn to scale. The figures are included to provide an illustration anda further understanding of the various aspects and embodiments, and areincorporated in and constitute a part of this specification, but are notintended as a definition of the limits of any particular embodiment. Thedrawings, together with the remainder of the specification, serve toexplain principles and operations of the described and claimed aspectsand embodiments. In the figures, each identical or nearly identicalcomponent that is illustrated in various figures is represented by alike numeral. For purposes of clarity, not every component may belabeled in every figure. In the figures:

FIG. 1 illustrates a circuit diagram of a conventional online UPS;

FIG. 2 illustrates a schematic diagram of a UPS according to anembodiment;

FIG. 3 illustrates a process of controlling the UPS according to anembodiment;

FIG. 4 illustrates a circuit diagram of the UPS including a firstcurrent path according to an embodiment;

FIG. 5 illustrates a circuit diagram of the UPS including a secondcurrent path according to an embodiment;

FIG. 6 illustrates a circuit diagram of the UPS including a thirdcurrent path according to an embodiment;

FIG. 7 illustrates a circuit diagram of the UPS including a fourthcurrent path according to an embodiment;

FIG. 8 illustrates a circuit diagram of the UPS including a fifthcurrent path according to an embodiment;

FIG. 9 illustrates a circuit diagram of the UPS including a sixthcurrent path according to an embodiment;

FIG. 10 illustrates a circuit diagram of the UPS including a seventhcurrent path according to an embodiment;

FIG. 11 illustrates a circuit diagram of the UPS including an eighthcurrent path according to an embodiment;

FIG. 12 illustrates a schematic diagram of a UPS according to anembodiment;

FIG. 13 illustrates a schematic diagram of a UPS according to anembodiment; and

FIG. 14 illustrates a schematic diagram of a UPS according to anembodiment.

DETAILED DESCRIPTION OF THE INVENTION

Examples of the methods and systems discussed herein are not limited inapplication to the details of construction and the arrangement ofcomponents set forth in the following description or illustrated in theaccompanying drawings. The methods and systems are capable ofimplementation in other embodiments and of being practiced or of beingcarried out in various ways. Examples of specific implementations areprovided herein for illustrative purposes only and are not intended tobe limiting. In particular, acts, components, elements and featuresdiscussed in connection with any one or more examples are not intendedto be excluded from a similar role in any other examples.

Also, the phraseology and terminology used herein is for the purpose ofdescription and should not be regarded as limiting. Any references toexamples, embodiments, components, elements or acts of the systems andmethods herein referred to in the singular may also embrace embodimentsincluding a plurality, and any references in plural to any embodiment,component, element or act herein may also embrace embodiments includingonly a singularity. References in the singular or plural form are nointended to limit the presently disclosed systems or methods, theircomponents, acts, or elements. The use herein of “including,”“comprising,” “having,” “containing,” “involving,” and variationsthereof is meant to encompass the items listed thereafter andequivalents thereof as well as additional items. References to “or” maybe construed as inclusive so that any terms described using “or” mayindicate any of a single, more than one, and all of the described terms.In addition, in the event of inconsistent usages of terms between thisdocument and documents incorporated herein by reference, the term usagein the incorporated features is supplementary to that of this document;for irreconcilable differences, the term usage in this documentcontrols.

As discussed above, certain UPSs, including online UPSs, can includemultiple power conversation stages. For example, a conventional onlineUPS may include an input PFC converter and a separate DC/DC convertercoupled to an energy storage device to convert the input AC power andstored DC power, respectively. FIG. 1 illustrates a circuit diagram of aconventional online UPS 100 including multiple input power conversionstages. The online UPS 100 includes a PFC converter 102, a DC/DCconverter 104, an inverter 106, and a controller 107. An input of thePFC converter 102 is configured to be coupled to an AC power source 108and an output of the PFC converter 102 is coupled to the inverter 106via a first DC bus 110 and a second DC bus 112. The DC/DC converter 104is configured to be coupled to an energy storage device 114 and iscoupled to the inverter 106 via the first DC bus 110 and the second DCbus 112. The inverter 106 is configured to be coupled to, and provideoutput power to, a load 116. The controller 107 is communicativelycoupled to, and may provide control signals to, one or more switchingdevices (for example, transistors) in the UPS 100.

Responsive to receiving input AC power from the AC power source 106, thePFC converter 102 is configured to convert the received AC power to DCpower and provide the DC power to the inverter 106 via the first DC bus110 and the second DC bus 112. If the energy storage device 114 is notfully charged, then the PFC converter 102 may also provide a portion ofthe DC power to the DC/DC converter 104 to charge the energy storagedevice 114 via the first DC bus 110 and the second DC bus 112.

Responsive to the AC power source 106 being unable to provide sufficientAC power to the PFC converter 102 (for example, due to a blackout orbrownout condition), the DC/DC converter 104 may be configured to entera backup mode of operation. In the backup mode of operation, the DC/DCconverter 104 may be configured to draw backup DC power from the energystorage device 114, convert the backup DC power to converted DC power(for example, by changing a voltage level of the energy stored in theenergy storage device 114), and provide the converted DC power to theinverter 106 via the first DC bus 110 and the second DC bus 112. Theinverter 106 is configured to convert DC power from the first DC bus 110and the second DC bus 112 (derived from at least one of the input ACpower or the backup DC power as described above) into output AC powerand the output AC power is provided to the load 116.

A size, component count, and cost of the conventional online UPS 100 maybe disadvantageously high, for example, in part due to the PFC converter102 and the DC/DC converter 104 being implemented as separateconverters. The PFC converter 102 may be inactive when the DC/DCconverter 104 is active, and the DC/DC converter 104 may be inactivewhen the PFC converter 102 is active. Thus, it may be beneficial toprovide a single converter topology capable of performing functions ofthe PFC converter 102 and the DC/DC converter 104 without extendedperiods of inactivity to reduce the size, component count, and cost ofan online UPS in which such a converter would be implemented.

The conventional online UPS 100 may also be disadvantageous because thepower provided to the first DC bus 110 and the second DC bus 112typically is not independently controlled in the backup mode ofoperation. For example, power provided by the PFC converter 102 and theDC/DC converter 104 to the first DC bus 110 and the second DC bus 112 isprovided in equal proportions, without regard for the demands of theload 116. This may result in inefficient operation of the conventionalonline UPS 100. For instance, the conventional online UPS 100 may beunable to efficiently provide power to a load requiring an unevendistribution of power from the busses 110, 112 in a backup mode ofoperation, such as a load requiring a half-wave rectified waveform drawnprimarily from the first DC bus 110.

In view of the foregoing, the conventional online UPS 100 may bedisadvantageously costly, large, and inflexible. Accordingly, aspects ofthe present disclosure provide a topology capable of addressing at leastsome of the foregoing deficiencies to reduce costs and improveefficiency of a UPS.

FIG. 2 illustrates a schematic diagram of a UPS 200 according to oneembodiment described herein. The UPS 200 includes a dual converter 202,an inverter 204, and a controller 205. The dual converter 202 isconfigured to be coupled to an AC power source 206, and is coupled tothe inverter 204. The inverter 204 is coupled to the dual converter 202,and may be configured to be coupled to a load.

The dual converter 202 includes a primary branch 208 and a backup branch210. The primary branch 208 includes a first relay 212, a first diode214, a second diode 216, a first inductor 218, a second inductor 220, afirst switching device 222, a third diode 224, and a fourth diode 226.The backup branch 210 includes an energy storage device 228, a secondrelay 230, a third inductor 232, a fourth inductor 234, a secondswitching device 236, and a third switching device 238. In someexamples, the energy storage device 228 may be external to the dualconverter 202 and may be coupled to the backup branch 210. The inverter204 may include a fifth diode 240, a sixth diode 242, a first capacitor244, a second capacitor 246, a fourth switching device 248, a fifthswitching device 250, a fifth inductor 252, and a third capacitor 254.

In some embodiments, other inverter topologies may be implemented inlieu of, or in addition to, the topology illustrated in connection withthe inverter 204. In other embodiments, the inverter 204 may be omittedsuch that the UPS 200 provides DC, rather than AC, output power. Instill other embodiments, the components 240-254 of the inverter 204 maybe implemented as illustrated in FIG. 2 , but the switching devices 248,250 be operated to provide DC, rather than AC, output power. Forexample, only one of the switching devices 248, 250 may be closed andconducting while providing output power to the load 256, such that powerhaving only one voltage polarity is provided to the load 256. Thus,although the components 240-254 are described in one example as beingcomponents of the inverter 204, the components 240-254 may be operatedto provide either DC or AC output power as required or desired by theload 256. The inverter 204, or a circuit implemented in lieu of theinverter 204, may be referred to herein as an “output circuit.”

In at least one embodiment, the first relay 212 is configured as asingle-pole double-throw switching device having a first terminal, asecond terminal, and a third terminal. The third terminal is configuredto be switchably connected to one of the first terminal and the secondterminal. The first terminal is configured to be coupled to the AC powersource 206. The second terminal is coupled to a reference node 213 (forexample, a node at a reference voltage such as a ground voltage). Thethird terminal is configured to be coupled to the first diode 214 andthe second diode 216. The first diode 214 has an anode coupled to thefirst relay 212 and the second diode 216, and a cathode coupled to thefirst inductor 218. The second diode 216 has a cathode coupled to thefirst relay 212 and the first diode 214, and an anode coupled to thesecond inductor 220.

The first inductor 218 is coupled to the first diode 214 at a firstconnection, and is coupled to the first switching device 222, the thirddiode 224, and the fifth diode 240 at a second connection. The firstinductor 218 is further configured to be magnetically coupled to thethird inductor 232. As used herein, “magnetically coupled” may refer toa relationship of at least two inductive components in which a magneticfield and/or a change in a magnetic field produced by a first inductivecomponent induces a voltage across a second inductive component (forexample, mutual inductance).

The second inductor 220 is coupled to the second diode 216 at a firstconnection, and is coupled to the first switching device 222, the fourthdiode 226, and the sixth diode 242 at a second connection. The secondinductor 220 is further configured to be magnetically coupled to thefourth inductor 234. The first switching device 222 is coupled to thefirst inductor 218, the third diode 224, and the fifth diode 240 at afirst connection, is coupled to the second inductor 220, the fourthdiode 226, and the sixth diode 242 at a second connection, and isconfigured to be communicatively coupled to the controller 205 at acontrol connection. The third diode 224 includes a cathode connectioncoupled to the first inductor 218, the first switching device 222, andthe fifth diode 240, and an anode connection coupled to the fourth diode226 and the reference node 213. The fourth diode 226 includes a cathodeconnection coupled to the third diode 224 and the reference node 213,and an anode connection coupled to the second inductor 220, the firstswitching device 222, and the sixth diode 242.

The energy storage device 228 is coupled to the second relay 230 at afirst connection, and is coupled to the second switching device 236 andthe third switching device 238 at a second connection. In at least oneembodiment, the second relay 230 is configured as a single-polesingle-throw switch having a first terminal, a second terminal, and athird terminal. The third terminal is configured to be switchablyconnected to one of the first terminal and the second terminal. Thefirst terminal is configured to be coupled to the third inductor 232 andthe fourth inductor 234. In an embodiment, the second terminal may notbe permanently connected to any other component, and is configured to beswitchably connected to the third terminal. Accordingly, in anembodiment, current does not pass through the second terminal. The thirdterminal is configured to be coupled to the energy storage device 228.In some examples, the energy storage device 228 may be coupled to acharger (not illustrated) configured to charge the energy storage device228. For example, a charger may be coupled in parallel with the energystorage device 228.

The third inductor 232 is coupled to the second relay 230 at a firstconnection, and is coupled to the second switching device 236 at asecond connection. The fourth inductor 234 is coupled to the secondrelay 230 at a first connection, and is coupled to the third switchingdevice 238 at a second connection. The second switching device 236 iscoupled to the third inductor 232 at a first connection, is coupled tothe energy storage device 228 at a second connection, and is configuredto be communicatively coupled to the controller 205 at a controlconnection. The third switching device 238 is coupled to the fourthinductor 234 at a first connection, is coupled to the energy storagedevice 228 at a second connection, and is configured to becommunicatively coupled to the controller 205 at a control connection.

The fifth diode 240 has an anode coupled to the first inductor 218, thefirst switching device 222, and the third diode 224, and a cathodecoupled to the first capacitor 244 and the fourth switching device 248.The sixth diode 242 has a cathode coupled to the second inductor 220,the first switching device 222, and the fourth diode 226, and an anodecoupled to the second capacitor 246 and the fifth switching device 250.The first capacitor 244 is coupled to the fifth diode 240 and the fourthswitching device 248 at a first connection, and is coupled to thereference node 213 at a second connection. The second capacitor 246 iscoupled to the reference node 213 at a first connection, and is coupledto the sixth diode 242 and the fifth switching device 250 at a secondconnection.

The fourth switching device 248 is coupled to the fifth diode 240 andthe first capacitor 244 at a first connection, is coupled to the fifthswitching device 250 and the fifth inductor 252 at a second connection,and is configured to be communicatively coupled to the controller 205 ata control connection. The fifth switching device 250 is coupled to thefourth switching device 248 and the fifth inductor 252 at a firstconnection, is coupled to the sixth diode 242 and the second capacitor246 at a second connection, and is configured to be communicativelycoupled to the controller 205 at a control connection.

The fifth inductor 252 is coupled to the fourth switching device 248 andthe fifth switching device 250 at a first connection, and is configuredto be coupled to the third capacitor 254 at a second connection. Thethird capacitor 254 is coupled to the fifth inductor 252 at a firstconnection, and is coupled to the reference node 213 at a secondconnection. In some examples, the third capacitor 254 may be configuredto be coupled to a load external to the UPS 200. For example, the thirdcapacitor 254 may be configured to be coupled in parallel with a load.

The dual converter 202 is configured to receive input power from atleast one of the AC power source 206 and the energy storage device 228,convert the received power to DC power (for example, from AC power or DCpower of a different voltage level), and provide the converted DC powerto the inverter 204. The inverter 204 is configured to receive the DCpower from the dual converter 202, convert the received DC power tooutput AC power, and provide the output AC power to a load. Thecontroller 205 is configured to control the dual converter 202 and theinverter 204. For example, controlling operation of the dual converter202 and the inverter 204 may include controlling a switching operationof the first switching device 222, the second switching device 236, thethird switching device 238, the fourth switching device 248, and thefifth switching device 250.

The controller 205 may determine a mode of operation of the UPS 200 and,based on the mode of operation, control the dual converter 202 to drawpower from at least one of the AC power source 206 or the energy storagedevice 228. For example, the controller 205 may determine a quality ofpower provided by the AC power source 206 based on one or more receivedparameters (for example, voltage, current, frequency, etc.) indicativeof the quality of power provided by the AC power source 206. Determininga quality of power provided by the AC power source 206 may include, forexample, determining if a parameter indicative of the power quality (forexample, a voltage or current parameter) is within a permissible range.

If the parameter indicative of the power quality is within thepermissible range, the controller 205 may determine that the UPS 200 isin a normal mode of operation characterized at least partially by theUPS 200 receiving acceptable-quality power from the AC power source 206.In the normal mode of operation, the controller 205 may control the dualconverter 202 to draw power from the AC power source 206. If theparameter indicative of the power quality is outside of the permissiblerange, the controller 205 may determine that the UPS 200 is in a backupmode of operation characterized at least partially by the UPS 200 beingunable to receive acceptable-quality power from the AC power source 206.In the backup mode of operation, the controller 205 may control the dualconverter 202 to draw power from the energy storage device 228.

FIG. 3 illustrates a process 300 of controlling the UPS 200 according toan embodiment. At act 302, the process 300 begins. At act 304, adetermination is made as to whether the UPS 200 is in a normal mode ofoperation. For example, as discussed above, the controller 205 maydetermine whether the UPS 200 is in the normal mode of operation basedon one or more parameters indicative of a quality of power provided bythe AC power source 206. If the controller 205 determines that the UPS200 is in a normal mode of operation (304 YES), then the process 300continues to act 306.

At act 306, the controller 205 controls the first relay 212 and thesecond relay 230. Controlling the first relay 212 includes connectingthe third terminal of the first relay 212 to the first terminal of thefirst relay 212 such that the AC power source 206 is coupled to thefirst diode 214 and the second diode 216 via the first relay 212.Controlling the second relay 230 includes connecting the third terminalof the second relay 230 to the second terminal of the second relay 230such that the energy storage device 228 is disconnected from the thirdinductor 232 and the fourth inductor 234.

At act 308, the first inductor 218 is energized. In one embodiment, thefirst inductor 218 is energized at act 308 by AC power received from theAC power source 206 where the AC power is in a positive half-cycle of asinusoidal waveform. In one example, the first diode 214 isforward-biased and the second diode 216 is reverse-biased during apositive half-cycle of power provided by the AC power source 206.Energizing the first inductor 218 includes controlling, by thecontroller 205, the first switching device 222 to alternate between anopen and non-conducting position and a closed and conducting position.The controller 205 may control the first switching device 222 inaccordance with the power received from the AC power source 206. Forexample, the controller 205 may control the first switching device 222to maintain a sinusoidal current through the first switching device 222from the AC power source 206.

When the first switching device 222 is in a closed and conductingposition, AC power provided by the AC power source 206 is delivered to aconductive path including the AC power source 206, the first relay 212,the first diode 214, the first inductor 218, the first switching device222, and the fourth diode 226. FIG. 4 illustrates a circuit diagram ofthe UPS 200 indicating a current path 400 at act 308.

At act 310, the first inductor 218 is de-energized. For example, act 310includes controlling, by the controller 205, the first switching device222 to transition from a closed and conducting position to an open andnon-conducting position, thereby interrupting the current path 400. Thefirst inductor 218 discharges to a conductive path including the ACpower source 206, the first relay 212, the first diode 214, the firstinductor 218, the fifth diode 240, and the first capacitor 244 to chargethe first capacitor 244. FIG. 5 illustrates a circuit diagram of the UPS200 indicating a current path 500 at act 310.

As discussed above, the first inductor 218 is magnetically coupled tothe third inductor 232. However, during acts 308 and 310, the secondswitching device 236 is maintained in an open and non-conductingposition. Accordingly, although a voltage is induced across the thirdinductor 232, no induced current passes through the third inductor 232during acts 308 and 310 at least because the third inductor 232 iscoupled in series with the open and non-conducting second switchingdevice 236.

At act 312, the second inductor 220 is energized. In one embodiment, thesecond inductor 220 is energized at act 312 by power received from theAC power source 206 where the AC power provided by the AC power source206 is in a negative half-cycle of the sinusoidal waveform. In oneexample, the first diode 214 is reverse-biased and the second diode 216is forward-biased during a negative half-cycle of power provided by theAC power source 206. Energizing the second inductor 220 may includecontrolling, by the controller 205, the first switching device 222 to bein a closed and conducting position such that power provided by the ACpower source 206 is delivered to a conductive path including the ACpower source 206, the second diode 216, the second inductor 220, thefirst switching device 222, and the third diode 224. Controlling thefirst switching device 222 at act 312 may be executed similarly tocontrolling the first switching device 222 as discussed above withrespect to act 308. FIG. 6 illustrates a circuit diagram of the UPS 200indicating a current path 600 at act 312.

At act 314, the second inductor 220 is de-energized. For example, act314 includes controlling, by the controller 205, the first switchingdevice 222 to transition from a closed and conducting position to anopen and non-conducting position, thereby interrupting the current path600. The second inductor 220 discharges to a conductive path includingthe AC power source 206, the first relay 212, the second diode 216, thesecond inductor 220, the sixth diode 242, and the second capacitor 246to charge the second capacitor 246. FIG. 7 illustrates a circuit diagramof the UPS 200 indicating a current path 700 at act 314.

As discussed above, the second inductor 220 is magnetically coupled tothe fourth inductor 234. However, during acts 312 and 314, the thirdswitching device 238 is maintained in an open and non-conductingposition. Accordingly, although a voltage is induced across the fourthinductor 234, no induced current passes through the fourth inductor 234during acts 312 and 314 at least because the fourth inductor 234 iscoupled in series with the open and non-conducting third switchingdevice 238.

Accordingly, acts 308 and 310 are executed during a positive half-cycleof input power received from the AC power source 206 to charge the firstcapacitor 244, and acts 312 and 314 are executed during a negativehalf-cycle of input power received from the AC power source 206 tocharge the second capacitor 246. The inverter 204 may be controlledduring execution of acts 308-314 to draw power from the first capacitor244 and the second capacitor 246, convert the power to AC power, andprovide the AC power to an output. For example, the controller 205 mayuse Pulse Width Modulation (PWM) in connection with control signalsprovided to the switches 248, 250 to provide the AC power to the output.After act 314, the process 300 returns to act 304.

Responsive to determining that the UPS 200 is still in the normal modeof operation (304 YES), acts 306-314 are repeated. Responsive todetermining that the UPS 200 is not in the normal mode of operation (304NO), the process 300 continues to act 316. At act 316, the controller205 controls the first relay 212 and the second relay 230. Controllingthe first relay 212 may include connecting the third terminal of thefirst relay 212 to the second terminal of the first relay 212 such thatthe AC power source 206 is disconnected from the UPS 200, and the firstdiode 214 and the second diode 216 are coupled to the reference node213. Controlling the second relay 230 may include connecting the thirdterminal of the second relay 230 to the first terminal of the secondrelay 230 such that the energy storage device 228 is connected to thethird inductor 232 and the fourth inductor 234.

At act 318, the first inductor is energized. For example, act 318 mayinclude controlling, by the controller 205, the second switching device236 to be in a closed and conducting position to energize the thirdinductor 232. Because the third inductor 232 is magnetically coupled tothe first inductor 218, a voltage is induced across the first inductor218, thereby energizing the magnetically coupled first inductor 218.Energizing the third inductor 232, and consequently the first inductor218, may include providing, by the energy storage device 228, power tothe third inductor 232 in a conductive path including the energy storagedevice 228, the second relay 230, the third inductor 232, and the secondswitching device 236. FIG. 8 illustrates a circuit diagram of the UPS200 indicating a current path 800 at act 318.

Although the first inductor 218 is energized by the energization of themagnetically coupled third inductor 232, the first diode 214 preventsthe first inductor 218 from discharging. The induced voltage across thefirst inductor 218 reverse-biases the first diode 214, which is coupledin series with the first inductor 218, thereby preventing any inducedcurrent from passing through the first inductor 218 during act 318.

At act 320, the first inductor is de-energized. For example, act 320 mayinclude controlling, by the controller 205, the second switching device236 to be in an open and non-conducting position, thereby preventing theenergy storage device 228 from discharging to the third inductor 232.Responsive to the cessation of current through the third inductor 232,the polarity of the induced voltage across the first inductor 218 isreversed, thereby forward-biasing the first diode 214.

The first inductor 218 is therefore able to discharge current to aconductive path including the first relay 212, the first diode 214, thefirst inductor 218, the fifth diode 240, and the first capacitor 244 tocharge the first capacitor 244. FIG. 9 illustrates a circuit diagram ofthe UPS 200 indicating a current path 900 at act 320.

At act 322, the second inductor is energized. For example, act 322 mayinclude controlling, by the controller 205, the third switching device238 to be in a closed and conducting position to energize the fourthinductor 234. Because the fourth inductor 234 is magnetically coupled tothe second inductor 220, a voltage is induced across the second inductor220, thereby energizing the magnetically coupled second inductor 220.

Energizing the fourth inductor 234, and consequently the second inductor220, may include providing, by the energy storage device 228, power tothe fourth inductor 234 in a conductive path including the energystorage device 228, the second relay 230, the fourth inductor 234, andthe third switching device 238. FIG. 10 illustrates a circuit diagram ofthe UPS 200 indicating a current path 1000 at act 322.

Although the second inductor 220 is energized by the energization of themagnetically coupled fourth inductor 234, the second diode 216 preventsthe second inductor 220 from discharging. The induced voltage across thesecond inductor 220 reverse-biases the second diode 216, which iscoupled in series with the second inductor 220, thereby preventing anyinduced current from passing through the second inductor 220 during act322.

At act 324, the second inductor is de-energized. For example, act 324may include controlling, by the controller 205, the third switchingdevice 238 to be in an open and non-conducting position, therebypreventing the energy storage device 228 from discharging to the fourthinductor 234. Responsive to the cessation of current through the fourthinductor 234, the polarity of the induced voltage across the secondinductor 220 is reversed, thereby forward-biasing the second diode 216.

The second inductor 220 is therefore able to discharge current to aconductive path including the first relay 212, the second diode 216, thesecond inductor 220, the sixth diode 242, and the second capacitor 246to charge the second capacitor 246. FIG. 11 illustrates a circuitdiagram of the UPS 200 indicating a current path 1100 at act 324.

Accordingly, acts 318 and 320 are executed to provide input power fromthe energy storage device 228 to charge the first capacitor 244, andacts 322 and 324 are executed to provide input power from the energystorage device 228 to charge the second capacitor 246. The inverter 204may be controlled during execution of acts 318-324 to draw power fromthe first capacitor 244 and the second capacitor 246, convert the powerto AC power, and provide the AC power to an output. For example, thecontroller 205 may use Pulse Width Modulation (PWM) in connection withcontrol signals provided to the switches 248, 250 to provide the ACpower to the output. After act 324, the process 300 returns to act 304.

Accordingly, process 300 may be executed by the UPS 200 to provideoutput power to a load during a normal mode of operation (for example,when the quality of AC power received from the AC power source 206 isacceptable) and during a backup mode of operation (for example, when thequality of AC power received from the AC power source 206 is notacceptable). As discussed above, the UPS 200 may be advantageousrelative to certain UPSs, such as the conventional online UPS 100, atleast because a component count of the UPS 200 is reduced relative tothe conventional online UPS 100. The cost and physical footprint of theUPS 200 may therefore be reduced relative to the conventional online UPS100.

In at least one embodiment, the primary branch 208 may be galvanicallyisolated from the backup branch 210. As used herein, “galvanicallyisolated” may refer to a relationship between at least two components inwhich no direct current path exists between the at least two components.For example, the primary branch 208 may be magnetically coupled to thebackup branch 210 via the first inductor 218, the second inductor 220,the third inductor 232, and the fourth inductor 234, but does not have adirect current path via a physical conductive medium, such as a wire,bus, or other solid conductor. Moreover, the primary branch 208 and thebackup branch 210 may not share a common ground or return connection.Accordingly, the primary branch 208 may be referred to herein as beinggalvanically isolated from the backup branch 210.

Moreover, a respective amount of power provided to the first capacitor244 and the second capacitor 246 may be individually controlled. Forexample, during the normal mode of operation, the amount of powerprovided to the first capacitor 244 at act 310 (for example, the amountof power provided during a positive half-cycle of the input AC power)may be proportional to an amount of energy provided to the firstinductor 218 at act 308. The amount of energy provided to the firstinductor 218 may in turn be proportional to a duration of controllingthe first switching device 222 to be in a closed and conducting position(for example, by controlling a duty cycle of a control signal providedto the first switching device 222 by the controller 205). Accordingly,an amount of power provided to the first capacitor 244 at act 310 may beindividually controlled by the controller 205 at act 308.

Similar principles apply to the amount of power provided to the secondcapacitor 246 at acts 312 and 314. For example, during the normal modeof operation, the amount of power provided to the second capacitor 246at act 314 (for example, the amount of power provided during a negativehalf-cycle of the input AC power) may be proportional to an amount ofenergy provided to the second inductor 220 at act 312. The amount ofenergy provided to the second inductor 220 may in turn be proportionalto a duration of controlling the first switching device 222 to be in aclosed and conducting position (for example, by controlling the dutycycle of the control signal provided to the first switching device 222by the controller 205). Accordingly, an amount of power provided to thesecond capacitor 246 at act 314 may be controlled by the controller 205at act 312.

In some embodiments, the first capacitor 244 and the second capacitor246 may be individually charged and discharged. As used herein,“individual charging and discharging” may refer to charging ordischarging one component without directly affecting, or beingconstrained by, another component. Accordingly, the first capacitor 244may be charged or discharged at a first rate, and the second capacitor246 may be charged or discharged at a second rate, where the first rateis independent of the second rate.

During the backup mode of operation, the amount of power provided to thefirst capacitor 244 at act 318 (for example, the amount of powerprovided by the energy storage device 228 to the first capacitor 244)may be proportional to an amount of energy provided to the firstinductor 218 at act 318. The amount of energy provided to the firstinductor 218 may in turn be proportional to a duration of controllingthe second switching device 236 to be in a closed and conductingposition (for example, by controlling a duty cycle of a control signalprovided to the second switching device 236 by the controller 205),thereby energizing the third inductor 232. Accordingly, an amount ofpower provided to the first capacitor 244 at act 320 may be controlledby the controller 205 at act 318.

Similar principles apply to the amount of power provided to the secondcapacitor 246 at acts 322 and 324. For example, during the backup modeof operation, the amount of power provided to the second capacitor 246at act 324 (for example, the amount of power provided by the energystorage device 228 to the second capacitor 246) may be proportional toan amount of energy provided to the second inductor 220 at act 322. Theamount of energy provided to the second inductor 220 may in turn beproportional to a duration of controlling the third switching device 238to be in a closed and conducting position (for example, by controlling aduty cycle of a control signal provided to the third switching device238 by the controller 205). Accordingly, an amount of power provided tothe second capacitor 246 at act 324 may be controlled by the controller205 at act 322.

An amount of power provided to the first capacitor 244 and an amount ofpower provided to the second capacitor 246 may be individuallycontrolled. Individual control of the amount of power provided to thefirst capacitor 244 and the second capacitor 246 may enable the UPS 200to respond to load requirements more effectively. For example, if theUPS 200 provides power to a load requiring rectified power with apositive voltage, the UPS 200 may provide additional power to the firstcapacitor 244 to compensate for an increased amount of power being drawnfrom the first capacitor 244 by the inverter 206 to generate therectified power.

FIG. 12 illustrates a schematic diagram of a UPS 1200 according to anembodiment. The UPS 1200 includes a dual converter 1202, an inverter1204, and a controller 1205. The dual converter 1202 is configured to becoupled to an AC input 1206, and is coupled to the inverter 1204. Theinverter 1204 is coupled to the dual converter 1202, and may beconfigured to be coupled to a load. The dual converter 1202 includes aprimary branch 1208 and a backup branch 1210.

The UPS 1200 is similar to the UPS 200. For example, the inverter 1204,the controller 1205, and the primary branch 1208 are similar to theinverter 204, the controller 205, and the primary branch 208. The backupbranch 1210 is similar to the backup branch 210 with the secondswitching device 236 and the third switching device 238 of the backupbranch 210 replaced by a single switching device in the backup branch1210.

More specifically, the backup branch 1210 includes an energy storagedevice 1212, a relay 1214, a first inductor 1216, a second inductor1218, and a switching device 1220. The energy storage device 1212 iscoupled to the relay 1214 at a first connection, and is coupled to theswitching device 1220 at a second connection. The relay 1214 isconfigured as a single-pole single-throw switch having a first terminal,a second terminal, and a third terminal. The third terminal isconfigured to be switchably connected to one of the first terminal andthe second terminal. The first terminal is configured to be coupled tothe first inductor 1216 and the second inductor 1218. In an embodiment,the second terminal may not be permanently connected to any othercomponent, and is configured to be switchably connected to the thirdterminal. Accordingly, in an embodiment, current does not pass throughthe second terminal. The third terminal is configured to be coupled tothe energy storage device 1212.

The first inductor 1216 is coupled to the relay 1214 at a firstconnection, and is coupled to the switching device 1220 at a secondconnection. The second inductor 1218 is coupled to the relay 1214 at afirst connection, and is coupled to the switching device 1220 at asecond connection. The switching device 1220 is coupled to the firstinductor 1216 and the second inductor 1218 at a first connection, iscoupled to the energy storage device 1212 at a second connection, and isconfigured to be communicatively coupled to the controller 1205 at acontrol connection.

In some examples, the UPS 200 and the UPS 1200 are configured to operatesimilarly. For example, the UPSs 200, 1200 may operate in asubstantially similar fashion during a normal mode of operation. Duringa backup mode of operation, the first inductor 1216 and the secondinductor 1218 are not independently energized because the first inductor1216 and the second inductor 1218 are connected to the single, sharedswitching device 1220. In other words, the first inductor 1216 is notenergized without energizing the second inductor 1218, and the secondinductor 1218 is not energized without energizing the first inductor1216.

In contrast, the third inductor 232 can be energized independently ofthe fourth inductor 234 by closing the second switching device 236 andopening the third switching device 238, and the fourth inductor 234 canbe energized independently of the third inductor 232 by closing thethird switching device 238 and opening the second switching device 236.However, a component count of the UPS 1200 is less than a componentcount of the UPS 200 at least because the number of switching devices isreduced by one, thereby reducing the cost and footprint of the UPS 1200relative to the UPS 200.

FIG. 13 illustrates a schematic diagram of a UPS 1300 according to anembodiment. The UPS 1300 includes a dual converter 1302, an inverter1304, and a controller 1305. The dual converter 1302 is configured to becoupled to an AC input 1306, and is coupled to the inverter 1304. Theinverter 1304 is coupled to the dual converter 1302, and may beconfigured to be coupled to a load. The dual converter 1302 includes aprimary branch 1308 and a backup branch 1310.

The UPS 1300 is similar to the UPS 200. For example, the inverter 1304and the controller 1305 are similar to the inverter 204 and thecontroller 205. The primary branch 1308 is similar to the primary branch208 and has two additional diodes, and the backup branch 1310 is similarto the backup branch 210 and has an additional diode. More specifically,the primary branch 1308 includes a first relay 1312, a first diode 1314,a second diode 1316, a third diode 1318, a fourth diode 1320, a firstinductor 1322, a second inductor 1324, a first switching device 1326, afifth diode 1328, and a sixth diode 1330. The backup branch 1310includes an energy storage device 1332, a second relay 1334, a seventhdiode 1336, a third inductor 1338, a fourth inductor 1340, a secondswitching device 1342, and a third switching device 1344. In anotherembodiment, the primary branch 1308 may be replaced by an alternatetopology, such as that of the primary branch 208. In yet anotherembodiment, the backup branch 1310 may be replaced by an alternatetopology, such as that of the backup branch 210.

The first relay 1312 is configured as a single-pole double-throwswitching device having a first terminal, a second terminal, and a thirdterminal. The third terminal is configured to be switchably connected toone of the first terminal and the second terminal. The first terminal isconfigured to be coupled to the AC input 1306. The second terminal iscoupled to a reference node 1313 (for example, a node at a referencevoltage such as a ground voltage). The third terminal is configured tobe coupled to the first diode 1314 and the second diode 1316. The firstdiode 1314 has an anode coupled to the first relay 1312 and the seconddiode 1316, and a cathode coupled to the first inductor 1322 and thethird diode 1318. The second diode 1316 has a cathode coupled to thefirst relay 1312 and the first diode 1314, and an anode coupled to thefourth diode 1320 and the second inductor 1324.

The third diode 1318 has a cathode coupled to the first diode 1314 andthe first inductor 1322, and an anode coupled to the fourth diode 1320and the reference node 1313. The fourth diode 1320 has a cathode coupledto the third diode 1318 and the reference node 1313, and an anodecoupled to the second diode 1316 and the second inductor 1324. The firstinductor 1322 is coupled to the first diode 1314 and the third diode1318 at a first connection, and is coupled to the first switching device1326, the fifth diode 1328, and an eighth diode 1346 of the inverter1304 at a second connection. The first inductor 1322 is furtherconfigured to be magnetically coupled to the third inductor 1338 of thebackup branch 1310.

The second inductor 1324 is coupled to the second diode 1316 and thefourth diode 1320 at a first connection, and is coupled to the firstswitching device 1326, the sixth diode 1330, and a ninth diode 1348 ofthe inverter 1304 at a second connection. The second inductor 1324 isfurther configured to be magnetically coupled to the fourth inductor1340 of the backup branch 1310. The first switching device 1326 iscoupled to the first inductor 1322, the fifth diode 1328, and the eighthdiode 1346 at a first connection, is coupled to the second inductor1324, the sixth diode 1330, and the ninth diode 1348 at a secondconnection, and is configured to be communicatively coupled to thecontroller 1305 at a control connection.

The fifth diode 1328 includes a cathode connection coupled to the firstinductor 1322, the first switching device 1326, and the eighth diode1346, and an anode connection coupled to the sixth diode 1330 and thereference node 1313. The sixth diode 1330 includes a cathode connectioncoupled to the fifth diode 1328 and the reference node 1313, and ananode connection coupled to the second inductor 1324, the firstswitching device 1326, and the ninth diode 1348.

The second relay 1334 is configured as a single-pole single-throwswitching device having a first terminal, a second terminal, and a thirdterminal. The third terminal is configured to be switchably connected toone of the first terminal and the second terminal. The first terminal isconfigured to be coupled to the seventh diode 1336, the third inductor1338, and the fourth inductor 1340. In an embodiment, the secondterminal may not be permanently connected to any other component, and isconfigured to be switchably connected to the third terminal.Accordingly, in an embodiment, current does not pass through the secondterminal. The third terminal is configured to be coupled to the energystorage device 1332 and to the seventh diode 1336.

The seventh diode 1336 includes an anode connection configured to becoupled to the third terminal of the second relay 1334, and a cathodeconnection configured to be coupled to the first terminal of the secondrelay 1334. The third inductor 1338 is coupled to the first terminal ofthe second relay 1334 at a first connection, and is coupled to thesecond switching device 1342 at a second connection. The third inductor1338 is further configured to be magnetically coupled to the firstinductor 1322. The second inductor 1340 is coupled to the first terminalof the second relay 1334 at a first connection, and is coupled to thethird switching device 1344 at a second connection. The fourth inductor1340 is further configured to be magnetically coupled to the secondinductor 1324.

The second switching device 1342 is configured to be coupled to thethird inductor 1338 at a first connection, is configured to be coupledto the energy storage device 1332 at a second connection, and isconfigured to be communicatively coupled to the controller 1305 at acontrol connection. The third switching device 1344 is configured to becoupled to the fourth inductor 1340 at a first connection, is configuredto be coupled to the energy storage device 1332 at a second connection,and is configured to be communicatively coupled to the controller 1305at a control connection. The energy storage device 1332 is coupled tothe third terminal of the second relay 1334 at a first connection, andis coupled to the third inductor 1342 and the fourth inductor 1344 at asecond connection.

As discussed above, the primary branch 1308 is similar to the backupbranch 208 and includes the third diode 1318 and the fourth diode 1320.The third diode 1318 and the fourth diode 1320 provide power walk-in.Power walk-in may be advantageous where the UPS 1300 transitions from abackup mode of operation to a normal mode of operation. Subsequent tothe transition from the backup mode of operation to the normal mode ofoperation, the UPS 1300 may resume drawing power from the AC input 1306.The UPS 1300 may draw a significant amount of current from the AC input1306 upon being connected to the AC input 1306. Power walk-in refers toa feature of the UPS 1306 by which the current drawn from the AC input1306 is more gradually increased when transitioning from the backup modeof operation to the normal mode of operation.

As discussed above, the third diode 1318 and the fourth diode 1320 areconnected to the reference node 1313. The third diode 1318 and thefourth diode 1320 enable power walk-in by coupling components of the UPS1300 (including, for example, at least one of the first diode 1314, thesecond diode 1316, the first inductor 1322, and the second inductor1324) to the reference node 1313 via the third diode 1318 and the fourthdiode 1320 while the UPS 1300 transitions from the backup mode ofoperation to the normal mode of operation. Because the components arecoupled to the reference node 1313 during the transition, an amount ofcurrent drawn by the UPS 1300 from the AC source 1306 upon completion ofthe transition from the backup mode of operation to the normal mode ofoperation is reduced.

As discussed above, the backup branch 1310 is similar to the backupbranch 210 and additionally includes the seventh diode 1336, having acathode connection coupled to the first terminal of the second relay1334, which is coupled to the third inductor 1338 and the fourthinductor 1340, and an anode connection coupled to the third terminal ofthe second relay 1334, which is coupled to the energy storage device1332. The seventh diode 1336 enables a faster transition from a normalmode of operation to a backup mode of operation.

For example, in one embodiment, the UPS 1300 may transition from anormal mode of operation to the backup mode of operation. Accordingly,the controller 1305 may control the second relay 1334 to transition fromconnecting the third terminal to the second terminal (which may be aconfiguration of the second relay 1334 during the normal mode ofoperation) to connecting the third terminal to the first terminal (whichmay be a configuration of the second relay 1334 during the backup modeof operation). Before the second relay 1334 completes the transition,current from the energy storage device 1332 may be unable to pass fromthe third terminal of the second relay 1334 to the first terminal of thesecond relay 1334, because a conductive path through the second relay1334 is not yet completed.

In one example, the seventh diode 1336 being connected in parallel withthe second relay 1334 enables the energy storage device 1332 todischarge through a conductive path including the energy storage device1332, the seventh diode 1336, and at least one of the third inductor1338 and the second switching device 1342, or the fourth inductor 1340and the third switching device 1344, while the second relay 1334completes a transition from connecting the third terminal to the secondterminal to connecting the third terminal to the first terminal. Stateddifferently, because the seventh diode 1336 is connected in parallelwith the second relay 1334, the energy storage device 1332 is allowed todischarge through the seventh diode 1336 before the second relay 1334 isfully transitioned from a normal mode of operation configuration and abackup mode of operation configuration. Accordingly, the seventh diode1336 enables the energy storage device 1332 to begin discharging quicklyin a transition from a normal mode of operation to a backup mode ofoperation.

FIG. 14 illustrates a schematic diagram of a UPS 1400 according to anembodiment. The UPS 1400 includes a dual converter 1402, an inverter1404, and a controller 1405. The dual converter 1402 is configured to becoupled to an AC input 1406, and is coupled to the inverter 1404. Theinverter 1404 is coupled to the dual converter 1402, and is configuredto be coupled to a load 1408.

The UPS 1400 is similar to the UPS 200. For example, the dual converter1402, the inverter 1404, and the controller 1405 are similar to the dualconverter 202, the inverter 204, and the controller 205. The UPS 1400further includes a relay 1410 configured as a single-pole double-throwswitching device having a first terminal, a second terminal, and a thirdterminal. The third terminal is configured to be switchably connected toone of the first terminal and the second terminal. The first terminal isconfigured to be coupled to the AC input 1406. The second terminal iscoupled to the inverter 1404. The third terminal is configured to becoupled to the load 1408.

The relay 1410 is configured to enable a bypass mode of operation inaddition to the backup mode of operation and the normal mode ofoperation. In the bypass mode of operation, the third terminal of therelay 1410 is coupled to the first terminal of the relay 1410 such thatAC power provided by the AC input 1406 bypasses the dual converter 1402and the inverter 1404. In the normal mode of operation or the backupmode of operation, the third terminal of the relay 1410 is coupled tothe second terminal of the relay 1410 such that the AC input 1406provides input power to the dual converter 1402 such that the UPS 1400operates similarly to the UPS 200.

The controller 1405 may provide one or more control signals to the relay1410 to control the switching position of the relay 1410. For example,the controller 1405 may select the bypass mode of operation, therebycontrolling the relay 1410 to connect the third terminal of the relay1410 to the first terminal of the relay 1410, responsive to determiningthat the AC power provided by the AC input 1406 is of a sufficientlyhigh quality. Determining that the AC power is of the sufficiently highquality may include determining that a parameter of the AC power iswithin a threshold range.

For example, the controller 1405 may determine that the voltage of theAC power is within 1V of an ideal 120V sinusoidal waveform and that theAC power is therefore of a sufficiently high quality to provide directlyto the load 1408. Otherwise, and continuing with the foregoing example,if the voltage of the AC power is not within 1V of an ideal 120Vsinusoidal waveform, the controller 1405 may determine that the AC powershould be processed by the dual converter 1402 and the inverter 1404before being provided to the load 1408. Accordingly, the controller 1405may control the relay 1410 to connect the third terminal of the relay1410 to the second terminal and select one of the backup mode ofoperation or the normal mode of operation.

As discussed above, UPSs disclosed herein may be controlled bycontrollers including the controller 205, the controller 1205, thecontroller 1305, and the controller 1405. Using data stored inassociated memory, the controllers may execute one or more instructionsstored on one or more non-transitory computer-readable media that mayresult in manipulated data. In some examples, the controllers mayinclude one or more processors or other types of controllers. In anotherexample, the controllers include a Field-Programmable Gate Array (FPGA)controller.

In yet another example, the controllers perform a portion of thefunctions disclosed herein on a processor and performs another portionusing an Application-Specific Integrated Circuit (ASIC) tailored toperform particular operations. As illustrated by these examples,examples in accordance with the present invention may perform theoperations described herein using many specific combinations of hardwareand software and the invention is not limited to any particularcombination of hardware and software components.

As discussed above, the UPS 200 may receive power from the energystorage device 228, which may be internal to, or external to and coupledto, the UPS 200. In some embodiments, the energy storage device 228 maybe coupled to an external charging device (not illustrated) configuredto charge the energy storage device 228 with electrical energy. Inalternate embodiments, the dual converter 202 may be configured torecharge the energy storage device 228 with energy derived from the ACpower source 206.

For example, recharging the energy storage device 228 may includecontrolling the second relay 230 and at least one of the secondswitching device 236 and the third switching device 238 to provide aconductive path including the energy storage device 228, the secondrelay 230, and either one or both of the third inductor 232 and thesecond switching device 236, and the fourth inductor 234 and the thirdswitching device 238. At least a portion of the power provided by the ACpower source 206 may be provided to the energy storage device 228 tocharge the energy storage device 228 via at least one of the firstinductor 218 and the third inductor 232, and the second inductor 220 andthe fourth inductor 234.

In one example, charging the energy storage device 228 may includecontrolling the second relay 230 to connect the third terminal of thesecond relay 230 to the first terminal of the second relay 230 andcontrolling the second switching device 236 to be in a closed andconducting position during a positive half-cycle of AC power provided bythe AC power source 206. The first inductor 218 may be energized by thepositive half-cycle of the AC power provided by the AC power source 206and energize the magnetically coupled third inductor 232. The thirdinductor 232 may discharge induced current to the energy storage device228 through a conductive path including the energy storage device 228,the second relay 230, the third inductor 232, and the second switchingdevice 236, thereby charging the energy storage device 228.

In another example, charging the energy storage device 228 may includecontrolling the second relay 230 to connect the third terminal of thesecond relay 230 to the first terminal of the second relay 230 andcontrolling the third switching device 238 to be in a closed andconducting position during a negative half-cycle of AC power provided bythe AC power source 206. The second inductor 220 may be energized by thenegative half-cycle of the AC power provided by the AC power source 206and energize the magnetically coupled fourth inductor 234. The fourthinductor 234 may discharge induced current to the energy storage device228 through a conductive path including the energy storage device 228,the second relay 230, the fourth inductor 234, and the third switchingdevice 238, thereby charging the energy storage device 228.

In light of the foregoing remarks, UPSs having reduced size andcomponent counts with increased flexibility have been described herein.In one example, a UPS having a dual converter has been described. Thedual converter includes components configured to operate during a backupmode of operation and a normal mode of operation, whereas certainconventional UPSs include a first set of components to operate during abackup mode of operation, and a second set of components to operateduring a normal mode of operation. Furthermore, the dual converter isconfigured to control an amount of power provided to each individual DCbus capacitor, whereas certain conventional UPSs are only capable ofproviding an equal amount of power each DC bus capacitor. Accordingly, acomponent count may be reduced, thereby lowering a cost and physicalsize of the UPS, while increasing the flexibility of the UPS.

Although certain embodiments have illustrated a dual converterimplemented in connection with a UPS, other exemplary converters may notbe implemented in connection with a UPS. The dual converter may beimplemented in any other environment or topology, and is not limited toexamples including UPSs. For example, the dual converter may beimplemented with a power device other than a UPS.

Having thus described several aspects of at least one embodiment of thisinvention, it is to be appreciated various alterations, modifications,and improvements will readily occur to those skilled in the art. Suchalterations, modifications, and improvements are intended to be part ofthis disclosure, and are intended to be within the spirit and scope ofthe invention. Accordingly, the foregoing description and drawings areby way of example only.

What is claimed is:
 1. An uninterruptible power supply (UPS) systemincluding: a first input configured to be coupled to an input powersource; a second input configured to be coupled to an energy storagedevice; an output configured to provide output power; a power conversioncircuit configured to convert power received from at least one of theinput power source or the energy storage device, the power conversioncircuit including: a primary branch portion having a first inductor anda third inductor, and a backup branch portion having a second inductor,the second inductor being magnetically coupled to, and galvanicallyisolated from, the first inductor, wherein the second inductor iscoupled to a first switching device and a fourth inductor beingmagnetically coupled to the third inductor, where the fourth inductor iscoupled to a second switching device; an output circuit coupled to thepower conversion circuit and to the output; and a controller coupled tothe power conversion circuit and to the output circuit, and configuredto: control the power conversion circuit to provide, in a normal mode ofoperation, direct current (DC) power derived from the input power sourceto the output circuit via the first inductor; control the powerconversion circuit to provide, in a backup mode of operation, DC powerderived from the energy storage device to the output circuit via thefirst inductor and the second inductor; control the first switchingdevice to induce a voltage across the first inductor and discharge thefirst inductor to charge a first capacitor; and control the secondswitching device to induce a voltage across the third inductor toprovide a second charging current to charge a second capacitor.
 2. TheUPS system of claim 1, wherein the output circuit includes a firstcapacitor configured to be coupled to the power conversion circuit and asecond capacitor configured to be coupled to the power conversioncircuit.
 3. The UPS system of claim 1, wherein the controller is furtherconfigured to control the first switching device to charge the firstcapacitor at a first rate and is configured to control the secondswitching device to charge the second capacitor at a second ratedifferent than the first rate.
 4. The UPS system of claim 1, wherein thecontroller is further configured to control the first switching deviceand the second switching device to charge the first capacitorsimultaneously with the second capacitor.
 5. The UPS system of claim 1,wherein controlling the first switching device to charge the firstcapacitor includes: controlling the first switching device to enable theenergy storage device to provide current to the second inductor, whereinproviding current to the second inductor includes inducing a voltageacross the first inductor; and controlling the first switching device todisable the energy storage device from providing current to the secondinductor, wherein the first inductor is configured to discharge thefirst charging current to the first capacitor responsive to theswitching device disabling the energy storage device.
 6. The UPS systemof claim 5, wherein controlling the second switching device to chargethe second capacitor includes: controlling the second switching deviceto enable the energy storage device to provide current to the fourthinductor, wherein providing current to the fourth inductor includesinducing a voltage across the third inductor; and controlling the secondswitching device to disable the energy storage device from providingcurrent to the fourth inductor, wherein the third inductor is configuredto discharge the second charging current to the second capacitorresponsive to the switching device disabling the energy storage device.7. The UPS system of claim 1, wherein the backup branch portion furtherincludes: a switching device having a first connection coupled to theenergy storage device and a second connection switchably coupled to thesecond inductor; and a diode having an anode connection coupled to thefirst connection of the switching device and a cathode connectioncoupled to the second connection of the switching device.
 8. The UPSsystem of claim 1, further comprising a switching device including: afirst connection coupled to the output; and a second connectionconfigured to be coupled to one of the output circuit or the firstinput, wherein the controller is configured to control the switchingdevice to connect the second connection to the first input in a bypassmode of operation, and is configured to control the switching device toconnect the second connection to the output circuit in the normal modeof operation and the backup mode of operation.
 9. The UPS system ofclaim 1, further comprising: a first diode having a cathode connectioncoupled to the first inductor, and an anode connection coupled to areference node; and a second diode having a cathode connection coupledto the reference node, and an anode connection coupled to the thirdinductor.
 10. A non-transitory computer-readable medium storing thereonsequences of computer-executable instructions for controlling a powerdevice comprising a first input to receive first input power, a secondinput to receive second input power, an output to provide output power,an output circuit including a first capacitor and a second capacitor toprovide the output power to the output, and a power conversion circuitincluding a primary branch portion having a first inductor coupled to afirst switching device and a third inductor coupled to the firstswitching device, and a backup branch portion having a second inductorcoupled to a second switching device and a fourth inductor coupled to athird switching device, the second inductor being magnetically coupledto the first inductor, and the fourth inductor being magneticallycoupled to the third inductor, the sequences of computer-executableinstructions including instructions that instruct at least one processorto: control the first switching device to provide the first input powerto the first inductor in a normal mode of operation; control the firstswitching device to discharge, by the first inductor in the normal modeof operation, first power derived from the first input power to theoutput circuit; control, in a backup mode of operation, the secondswitching device to induce a voltage across the first inductor anddischarge the first inductor to provide a first charging current to thefirst capacitor to charge the first capacitor; and control, in thebackup mode of operation, the third switching device to induce a voltageacross the third inductor and discharge the third inductor to provide asecond charging current to the second capacitor to charge the secondcapacitor.
 11. The non-transitory computer-readable medium of claim 10,the sequences of computer-executable instructions further includinginstructions that instruct the at least one processor to control thesecond switching device to provide the first charging current to thefirst capacitor at a first rate, and control the third switching deviceto provide the second charging current to the second capacitor at asecond rate, wherein the first rate is different than the second rateand wherein the first charging current is provided simultaneously withthe second charging current.
 12. The non-transitory computer-readablemedium of claim 10, wherein the power device further includes a fourthswitching device having a first connection coupled to the output, and asecond connection configured to be coupled to one of the output circuitor the first input, and wherein the sequences of computer-executableinstructions further include instructions that instruct the at least oneprocessor to control the fourth switching device to connect the secondconnection to the first input in a bypass mode of operation, and tocontrol the fourth switching device to connect the second connection tothe output circuit in the normal mode of operation and the backup modeof operation.
 13. A method for controlling a power device comprising afirst input to receive first input power, a second input to receivesecond input power, an output to provide output power, an output circuitincluding a first capacitor and a second capacitor to provide the outputpower to the output, and a power conversion circuit including a primarybranch portion having a first inductor and a third inductor, and abackup branch portion having a second inductor and a fourth inductor,the second inductor being magnetically coupled to the first inductor,and the fourth inductor being magnetically coupled to the thirdinductor, the method comprising: providing the first input power to thefirst inductor in a normal mode of operation; discharging, by the firstinductor in the normal mode of operation, first power derived from thefirst input power to the output circuit; inducing, in a backup mode ofoperation, a voltage across the first inductor and discharging the firstinductor to provide a first charging current to the first capacitor tocharge the first capacitor; and inducing, in the backup mode ofoperation, a voltage across the third inductor and discharging the thirdinductor to provide a second charging current to the second capacitor tocharge the second capacitor.
 14. The method of claim 13, the methodcomprising: providing the first charging current to the first capacitorat a first rate; and providing the second charging current to the secondcapacitor at a second rate, wherein the first rate is different than thesecond rate and wherein the first charging current is providedsimultaneously with the second charging current.
 15. The method of claim13, wherein the power device further includes a switching device havinga first connection coupled to the output, and a second connectionconfigured to be coupled to one of the output circuit or the firstinput, and wherein the method further comprises: controlling theswitching device to connect the second connection to the first input ina bypass mode of operation; and controlling the switching device toconnect the second connection to the output circuit in the normal modeof operation and the backup mode of operation.